ELECTRICITY 


  1. Electricity Basics

    1. What is static electricity?


Static electricity refers to electrical charge that builds up on a surface (and does not flow away). 


  1. What is an electrostatic series?


A chart that shows how strongly different materials hold on to electrons (and allows to determine which material will become positively-charged and which negatively-charged depending on what it is rubbed with). 


  1. What is an electrical ground? Why is it important?


Something that is able to remove a build-up of charge. It is important to prevent electric shocks and short-circuits.  


  1. What is lightning? How can fatal lightning strikes be prevented? 


Lightning is the discharge of electricity from the clouds to the earth. Lightning strikes can be prevented with a lightning rod. 


  1. How was the first battery invented? Who did this? When? 


Alessandro Volta created the first battery around 1800 by stacking alternating disks of zinc and copper separated by a cloth and electrolyte solution. 


  1. Insulators and Conductors

    1. Compare and contrast insulators and conductors. Give two examples of each. 


Conductors allow electricity to flow through them while insulators do not. Metals like iron and gold are conductors. Non-metals like rubber and plastic are insulators. 


  1. What is a semiconductor? Give an example of a material that is a semiconductor. Where are semiconductors used?


A semiconductor is a non-metal that is able to conduct electricity under certain conditions. Silicon is an example of a semiconductor. It is used widely in electronics. 


  1. What is a superconductor? How are superconductors made? What are some potential applications of superconductors? 


A superconductor is something that conducts electricity with no resistance. It is made by taking certain substances and making them very cold. Superconductors can be used to make perfectly efficient devices, with no energy waste. Can also be used for “quantum levitation”. 





  1. Measuring Electricity 

    1. What is the difference between voltage and current? What are their units (ie. Joules, Kilograms, Metres)?


Voltage is like the “pressure” of electricity while the current is like the amount of flow. Voltage is measured in Volts (V), which is a Joule per Coulomb (J/C). Current is measured in Amps (A), which is a Coulomb per second (C/s). 


  1. A technician finds that a certain load uses 50 V and runs a current of 4 A. What is the resistance across that load?


R = V/I 

R = 50 V/4A

R = 12.5 𝛀


  1. A 27 Ω resistor has a current of 3 A passing through it. What is the voltage? 


V = IR 

V = 3A x 27 Ω

V = 81 V


  1. Circuits
































  1. Power Generation

    1. How does a power plant generator work? How is this different from a simple motor?


A generator is a coil of wires inside a magnet. As the coils are spun inside the magnets, energy (electricity) is generated. A motor is the opposite of a generator. It is also made up of a coil of wires inside a magnet, except that electricity is put into the coils, magnetizing them, and causing motion. A generator uses motion to create electricity; a motor uses electricity to create motion!

  1. Compare and contrast the workings of a nuclear power plant with a coal power plant.


Both are non-renewable, and use a fuel source to generate heat, to boil water into steam, and then the steam spins a turbine (generator). Nuclear uses uranium, coal uses coal (which is a fossil fuel, mainly carbon). Nuclear is cleaner for the air, but may have a catastrophic meltdown. It also produces a lot of radioactive waste.  


  1. Name and describe three renewable energy sources.


Solar uses photovoltaic panels to convert sunlight into electricity. 

Hydro uses flowing water (like rivers) to spin turbines and generate electricity. 

Wind uses wind to spin turbines and generate electricity. 


  1. Why are renewable energy sources better than non-renewable? Give at least two reasons. 


  1. They do not run out!

  2. They tend to be cleaner and better for the environment. For instance, they release little or no greenhouse gases. 


  1. What was the Current War? Which figures are associated with each side? 


The Current War was fought between Thomas Edison, who promoted DC (direct current) power, and Nikola Tesla (together with George Westinghouse) who promoted AC (alternating current) power. Tesla and AC power won the war. Today, almost all power plants are AC. 






  1. Energy Consumption and Efficiency

    1. What is the basic unit of power? What is the unit of power commonly used at home?


Power is measured in Watts. At home, the basic unit is a kiloWatt-hour, kWh.  


  1. What is a phantom load? How can it be prevented? 


Phantom load refers to electricity that is being wasted while a device appears to be turned “off”. It can be prevented by unplugging the device. 


  1. A tablet device consumes 100 W when it is used. If it is used for 3 hours a day, four days a week, for six weeks, how much energy, in kW, does it consume? If the average cost of electricity is 12 cents per kWh, how much did it cost to operate the computer for the whole year? 


Usage = power x time 


Time = 3 hours a day x 4 days a week x 6 weeks = 72 hours 

Power = 100 W = 0.1 kW


Usage = 0.1 kW x 72 hours = 7.2 kWh


Cost = usage x rate 

Cost = 7.2 kWh x 12 cents per kWh = 86.4 cents


*or do it all in one step with this formula: Cost = power x time x rate


Cost = 0.1 kW x 3 x 4 x 6 x 12 cents 

Cost = 86.4 cents


  1. A toaster used 150,000 J to toast a bagel. The actual amount of energy required to toast a bagel is 120,000 J. How efficient is the toaster? 


% Efficiency = useful output/total input x 100

% Efficiency = 120,000 J/150,000 J x 100

% Efficiency = 80%